Direction ratios of PQ=(0−0,0−1,1−0)=(0,−1,1) Direction cosine =(∣0∣,​−2​1​​,​2​1​​)The given plane is x+y+z=3Direction ratios of the plane are (1,1,1) Length of the projection=0⋅1+1⋅2​1​+1⋅2​1​=2​2​=2​